Low operation voltage macromolecular composite memory assisted by graphene nanoflakes

The trend towards simple and low-cost processing is one of the most important for macromolecular memory development. Here, bistable memory devices using a solution-processable active material, a mixture of graphene nanoflakes (GNFs) and insulating poly(vinyl alcohol) (PVA), are investigated, which serve as the first example for the direct integration of as-prepared nanoscale graphene into macromolecular memory devices through a one-step low-temperature processing method. Bistable electrical switching behavior and nonvolatile rewritable memory effects are realized by using an indium-tin-oxide/GNF-PVA/ silver (ITO/GNF-PVA/Ag) sandwich structure. The resulting device exhibits low operation voltages of +1.4 V (turn-on) and -1.3 V (turn-off), which is promising for memory cells with low power consumptions. The programmable ON- and OFF-states possess a retention time of over 10⁴ s and endure up to 10⁷ read pulses. The carrier transport in the OFF- and ON-states follows the typical trap-limited space charge limited current and Ohmic laws, respectively. The asymmetric electrical switch behavior is therefore attributed to conducting filaments formed in the PVA layer assisted by the charged GNFs that induce the transition of the conductivity. Our study provides a potential approach for integrating as-prepared graphene into macromolecular memory devices with excellent performances through a simple solution-process.